human photosynthesis

how about convergence of light?

You would wind up walking around wearing a Solar Tower, a steam turbine generator, and an array of focusing mirrors, and still not come close to the energy output your body manages via its myriad metabolic processes.
Well... there is a sea slug that does it (one of the only known animals to obtain energy via direct photosynthesis if memory serves)

Wow I never thought non plant organisms could perform photosynthesis? Turns out there are three other animals that can do it besides the aforementioned slug, to various degrees:
Spotted Salamander - Ambystoma maculatum, Pea Aphid - Acyrthosiphon pisum and the Oriental Hornet - Vespa orientalis.